Attempt Number: 4
Error Message: Action not unique compared to other actions chosen from this state before. Choose a new action

Action Reasoning:
Block D needs to be on block C as per the goal. Since block D is clear and on the table, the next best action is to stack block B on block D, positioning correctly for subsequent actions to move other blocks without violating constraints.

New State Description:
Block A is on the table and clear. Block B is on block D and clear. Block C is on the table and clear. Block D is on the table and not clear. Block B is no longer in the hand. The hand is empty.

Action Chosen:
stack(block_b, block_d)
